Floating the panel with spacing for the edges also potentially makes clicking on icons more obnoxious, because instead of flinging your mouse down at high veloc

Floating the panel with spacing for the edges also potentially makes clicking on icons more obnoxious, because instead of flinging your mouse down at high velocity you now need to make sure it stops before the very edge. I say potentially because maybe they'll make the hitbox extend to the bottom edge. Knowing Microsoft though, I doubt it. It also is unnecessarily using space that I'd rather have for apps (not everyone has a high resolution monitor) and to my eye looks rather ugly. Definitely agree with you on the criticism of centered icons too, the position of items is now dynamic depending on how many icons are open which as you say is bad for muscle memory. There should be user studies being continuously done to converge on the best UI. A/B test the hell out of it and make it a science. Instead I get the feeling that it's ad-hoc with designers wanting to both leave a mark and copy macOS.